Chromium-nickel-alloys for wear application at elevated temperature

Chromium alloys are a promising class of materials for high temperature application. In this work we investigated the microstructure, hot hardness and sliding wear resistance against an Al2O3 counter-body of three Chromium-Nickel (CrNi) alloys. The microstructure of the investigated alloys consists of a Ni-rich and a Cr-rich phase and can be manipulated by heat treatments. In the solid solution annealed state the room temperature (RT) hardness of CrNi alloys exceeds 800 HV10. The most potent strengthening mechanism in this system is the super saturation of the Cr-rich phase with Ni. Consequently, solid solution annealed specimen experience a strong decline in hardness with the onset of diffusion and precipitation of Ni-rich precipitates within the Cr-rich phase. Aged specimens display a lower hardness at RT but show a lower relative decline in hardness at temperatures above 600 °C. Alloys with higher contents of Ni show a better performance at high temperature sliding wear due to the formation of stable mechanically mixed layers (MML). •CrNi alloys show a two-phase microstructure, which can be changed by heat treatment.•Strong solid solution strengthening in Cr-bcc phase leads to high hardness at RT.•Hot hardness is higher after solid solution annealing, but more stable after ageing.•Good wear resistance through formation of MML, which depends on Ni content.